Finland beat the United States 3-2 in Canada to seal their fifth World Junior Ice Hockey Championships title.
Seventeen-year-old Kaapo Kakko scored the winner in Vancouver's Rogers Arena before being named in the tournament's all-star team.
The Finns' other goals came from Jesse Ylonen and Otto Latvala, while the US goals came from Alexander Chmelevski and Josh Norris.
Kakko's winner came with just under 90 seconds remaining as Anton Lundell won the puck in the US zone.
Defenceman Henri Jokiharju then had a shot which was saved, but Kakko was able to backhand in the rebound past Cayden Primeau in the US goal.
"I can't think of a better guy to score that goal than Kaapo," Finland's goalkeeper Ukko-Pekka Luukkonen said.
"He deserved it.
"He played an awesome tournament."
Defenceman Oskari Laaksonen also called him an "unbelievable player".
"He showed today that he's a guy of big games, and he loves to play in the big games, it's great," he said.
US player Ryan Poehling described the game as one of "mistakes".
"We couldn't [capitalise] on the ones they did," he said.
"I think that was the difference in the game today."
The win sees Finland gain their third gold medal in six years, as well as the fifth in their history.
They have previously triumphed in 1987, 1998, 2014, 2016 and now 2019.
The day's other game saw Russia beat Switzerland 5-2 to grab the bronze medal.
Russia's captain Klim Kostin, who was booed by the crowd in the Rogers Arena, said it was "not a bad finish" to the tournament.
He scored Russia's fifth goal, while Kirill Slepets bagged a hat-trick and Nikita Shashkov picked up one.
Sleptets afterwards said it was his best performance of the tournament.
Switzerland's goals came from Valentin Nussbaumer and Tannick Bruschweiler.